The Federal Energy Regulatory Commission today accepted a new definition of the “bulk electric system” that changes which transmission lines and facilities must follow mandatory reliability standards.

In line with the advice of the North American Electric Reliability Corp., the proposal sets a strict threshold of 100 kilovolts, rather than giving regional grid overseers authority to choose what should count as part of the bulk electric system.

It includes a list of exemptions to that threshold.

Four FERC commissioners approved the new definition, while Commissioner Tony Clark recused himself.

Commissioner Cheryl LaFleur, a Democrat, said the vote highlights the commission’s good working relationship with NERC. The commission and NERC have been at odds in recent months, including FERC’s questioning earlier this year of the gird overseer’s spending and transparency (Greenwire, May 7).

“The road has sometimes been bumpy, but I think NERC and FERC have accomplished a lot together,” LaFleur said.

Commissioner Philip Moeller said this summer that the new definition was crucial for protecting the grid against blackouts like the outage that occurred in Southern California. Facilities handling less than 100 kV played a role in the outage last year after the failure of a high-voltage transmission line connecting Arizona and San Diego, FERC and NERC said last month (E&ENews PM, May 1).